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问题 选择题

汽车尾气中，氮的各种氧化物都可以通过灼热的铁粉转化为氮气消除其污染，其中一种的化学反应可表示为2X＋3FeFe3O4＋N2，则X的化学式为[ ]

A．N2O

B．NO

C．NO2

D．N2O5

答案

答案：C

单项选择题

Water is (41) important of all the things we (42) and drink. Not many people understand this, (43) it’s quite true. The human body (人体) can go (44) food for a long time, but two (45) three days without water can usually (46) people die.
Many people don’ t understand how much water the human body needs to work well and many people do not drink (47) , even (48) hot weather.
Our body is (49) water, about 65% to 75%, ff we do not have enough water, we’ll (50) tired and many will get ill. So you see, how important water is to us all.

[A] mostly[B] almost [C] most
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单项选择题

建设工程法律、行政法规、部门规章的效力从高到低依次为( )。

A．法律、行政法规、部门规章

B．法律、部门规章，行政法规

C．行政法规、法律、部门规章

D．部门规章、行政法规、法律
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